1. Field of the Invention
This invention relates to an isolator circuit with duty cycle feedback with synchronized input and isolated output circuits and with zener controlled amplitudes to maintain proportional average values.
2. Description of the Prior Art
In the utilization of analog electric signals for control purposes it is required on occasion to provide isolation between several devices utilizing the same signal so that the signal conductors may have common mode voltages that differ significantly in the several devices without affecting the value of the analog signal.
Heretofore, isolation has been provided by the procedure of transforming the analog signal to a proportional frequency of oscillation, transmitting the frequency through a non-conducting link such as an opto-coupler or transformer and finally transforming the frequency back to an analog signal. To achieve accuracy by this method requires a precisely controlled relationship, usually linear, between frequency and the analog signal for both transformations. Such precision is not easily obtained and is subject to degrading with aging of the apparatus.
The apparatus of my invention maintains the average values of the input and isolated output voltage in the face of circuit component variations caused by age and ambient conditions.